The present invention is directed generally to fuel cells and more particularly to a compliant cathode contact for a fuel cell.
Fuel cells are electrochemical devices which can convert energy stored in fuels to electrical energy with high efficiencies. One type of high temperature fuel cell is a solid oxide fuel cell which contains a ceramic (i.e., a solid oxide) electrolyte, such as a yttria stabilized zirconia (YSZ) electrolyte.
Fuel cell stacks, particularly those with planar geometry, often utilize an electrically conductive contact material to conduct electrons from the anode of one cell to the separator plate, and from the separator plate to the cathode of an adjacent cell. This material typically has a better electrical conductivity than the porous electrode (i.e., anode and/or cathode) material. This contact material may also provide flow distribution of oxygen- or fuel-bearing gases, in which case it may be referred to as a current conductor/gas flow distributor (“conductor/distributor” hereinafter). In some cases, these conductor/distributors may provide structural support to the fuel cell stack. Some examples of prior art conductor/distributors include metal wire coils, wire grids, and metal ribs. These may be used independently or in some combination.
The prior art conductor/distributors sometimes exhibit less-than-optimal current conduction or gas flow distribution properties. They are also costly to implement. Also, many of the prior art conductor/distributors are not compliant (i.e., not elastic at the fuel cell operating temperatures). Non-compliant components often present difficulties and increase costs in fabrication and assembly of the fuel cells due to the tighter fuel cell tolerances which are required.